1. Field of the Invention
This invention relates to a computer keyboard and more particularly to a multimedia computer keyboard embodying a speaker capable of producing computer-generated sound.
2. Background of the Relevant Art
Multimedia systems which produce computer-generated sound are well known. Early systems often employ transducers which produce a buzz or beep when activated. The buzzers or alarms which are mounted within the computer housing or mainframe are generally piezoelectric-type transducers. A sound card, also mounted within the mainframe, generates an electrical signal sent over a conductor coupled to the piezoelectric transducer. Once the transducer receives electrical stimulus, it responds by vibrating and thereby producing an acoustic pulse (i.e., a sound wave). The conversion of electrical energy to mechanical energy within certain crystalline or ceramic substances (termed "piezoelectric effect") is a well known phenomena which produces an efficient, solid state transducer.
Piezoelectric transducers, however, do not have the ability to produce high quality sound over a broad frequency spectrum. Generally speaking, piezoelectric transducers are used only to emit one or more beeps of slightly variable pitch. They do not and cannot produce high fidelity voice and music playback necessary in more advanced multimedia applications. Recent developments in computer-generated sound involve the use of electro-acoustic transducers of higher quality than the piezoelectric type.
Audio output from the sound card is generally of high quality (broad frequency response range, low distortion and high output). In order to take full advantage of high fidelity audio output, computer manufactures have begun to realize the importance of using higher quality sound reproduction using transducers such as diaphragm-type speakers. The diaphragm-type speakers are often mounted within an enclosure and placed adjacent the computer housing. Diaphragm-type speakers generally convert the electrical output from the sound card to field energy (magnetic or electric), wherein the field drives the diaphragm. The moving diaphragm produces sound waves detectable by the listener or operator. The diaphragm can consist of numerous shapes and sizes. Popular shapes include a cone, dome or metallic ribbon. Diaphragm-type speakers must be mounted within an enclosure so as to support the speaker drive units and provide necessary acoustic properties (e.g., radiation pattern and driver acoustic loading). The enclosure can be open backed or conceal a horn or other system folded into a compact structure within the enclosure. During use, the vibrating diaphragm will simultaneously excite the driver chassis or enclosure causing it to vibrate in symphony. The enclosure therefore must be carefully designed to prevent it from moving, and hence reducing the diaphragm output. If the energy transferred to the enclosure is not properly dissipated, the resonant modes of the enclosure may be audible thereby causing a reduction in the overall sound quality produced by the speaker.
Many conventional multimedia systems which use a diaphragm-type speaker are restricted to using a separate enclosure for the speaker and arranging the enclosed speaker adjacent the computer housing. Unfortunately, routing of conductor wires from the sound card to the speakers is often a nuisance. Separate wires must be purchased and routed from the speaker to the sound card audio output. Furthermore, an audio plug is needed which can couple the wires to the audio card connector. Connection of separate, enclosed speakers to the sound card is not only cumbersome, but it is also time consuming. Disconnect and reconnect is an unfortunate necessity each time the operator chooses to move his or her computer. The problems are particularly acute when using a portable computer. Separate enclosed speakers cannot as a practical matter be used with portable computers unless the operator is willing to carry the speakers, as separate items, with the computer--a burden which most consumers may be unwilling to bear.
In an effort to overcome the problems of using separate enclosed speakers, many multimedia systems often employ diaphragm-type speakers mounted directly on the computer housing or electronic display (monitor). By using the housing associated with the computer, the system can take advantage of higher quality diaphragm-type sound reproduction without the problems of having to connect separate wires between the speakers (mounted within the computer) and the computer. Thus, the speakers can be fully integrated into the computer or display for ease of portability.
Although integrated computer/speaker multimedia systems present many advances over remote speakers and associated cabling, speakers mounted within the computer housing or display suffer many drawbacks. In particular, the operator must face the computer or display in order to obtain the full benefits of audio reproduction. In most instances, the operator faces the keyboard and only periodically turns his or her attention to the display. The computer can often be hidden away from sight, as is the case in remotely placed, upright models. Audio playback from a remotely located speaker placed on the computer cannot utilize high fidelity reproduction to its maximum advantage. While speakers mounted within the display might be more advantageous than those mounted in the computer housing, speakers mounted in the display often require wires routed from the audio card (within the computer) to the separate display. Thus, display-mounted speakers suffer the same drawback as separate, remote speaker enclosures described above.
In order to overcome the problems with current multimedia systems, it would be advantageous to mount the speakers within the computer system for ease of portability. It would also be beneficial to ensure the speakers reside directly in front of the operator during times in which the operator is interfacing the system. Still further, it would be desirable to route the audio signal from the sound card to the diaphragm-type speaker through existing cables, conductors and connectors.